All electronics, except cell phones and approved medical devices, will be banned from cabins of U.S.-bound flights from international airports in Amman, Jordan; Kuwait City, Kuwait; Cairo; Istanbul; Jeddah and Riyadh, Saudi Arabia; Casablanca, Morocco; Doha, Qatar; and Dubai and Abu Dhabi in the United Arab Emirates. The new rule affects nine airlines.
The order comes after concerns over new intelligence that terrorists are targeting commercial aviation and trying to smuggle explosive devices into consumer items. In February 2016, an explosion from an electronic device left a gaping hole in an aircraft as it flew over East Africa. Everyone on the flight survived, except the terrorist.
The Department of Homeland Security has not mentioned a specific threat, but said they are aware terrorist groups are targeting commercial flights and trying to smuggle explosive devices into consumer items, which would be a concern for anyone flying.
"What's likely happened is that the U.S. government has developed some intelligence that a group or individual has developed some type of device that they can get onto an airplane using a laptop or some other electronic appliance," said Matt Olson, counter-terrorism expert.
"You try not to get overly anxious about it. You want to trust that people are doing their job correctly and you can fly safely," said Ken Njoroge, who flew into O'Hare Tuesday morning.
"It makes it difficult to plan, both for us and for the travelers, who we're trying to help here. So as people try to get through customs, they're trying to plan, on their end, what their trip is going to look like, what the difficulties they may encounter are," said Max Schleusener, a lawyer at O'Hare.
Travelers arriving in Chicago from Abu Dhabi in the United Arab Emirates were aware of the new ban. But since it went into effect during their flight, they still had their electronics in the cabin with them. But it will impact their future flights.
"People carry laptops and iPads for all kinds of reasons, related to work, related to daily life. If they can't bring it, what are they going to do?" said Amitava Dutt, a passenger.
To clarify, all electronics are still allowed on planes, but they must be checked. There is no word yet on how long the ban will last.
Senior Trump administration officials said airlines were to have 96 hours to implement the security order or face being barred from flying to the United States. The officials spoke on the condition of anonymity to discuss the security ban despite President Donald Trump's repeated insistence that anonymous source should not be trusted.
About 50 flights a day, all on foreign carriers, will be impacted. The officials said no U.S.-based airlines have non-stop flights from those cities to the United States.
The officials said the decision was prompted by "evaluated intelligence" about ongoing potential threats to airplanes bound for the United States. The officials would not discuss the timing of the intelligence or if any particular terror group is thought to be planning an attack.
Details of the ban were first disclosed by Royal Jordanian Airlines and the official news agency of Saudi Arabia.
In its statement, Royal Jordanian said the electronics ban would affect its flights to New York, Chicago, Detroit and Montreal.
Across the Atlantic early Tuesday, problems and confusion ensued.
Egyptian officials at the Cairo International Airport said they had not received any instructions on banning passengers from bringing laptops, iPads, cameras and some other electronics on board direct flights to the United States. The officials said a New York-bound EgyptAir flight departed and that passengers were allowed to take their laptops and other electronics on board in their carry-on luggage.
A spokesman for Royal Jordanian says the airliner has not yet started to enforce the new U.S. regulation. Basel Kilani has told The Associated Press that the airline was still awaiting formal instructions from the relevant U.S. departments, which could possibly come later on Tuesday.
However, the Mideast's biggest airline is confirming that U.S.-bound passengers will be prevented from carrying electronic gadgets aboard aircraft.
Dubai-based Emirates said Tuesday the ban takes effect on Saturday. That guidance differs from the information provided by senior Trump administration officials, who have said the ban is in place from Tuesday
Brian Jenkins, an aviation-security expert at the Rand Corp., said earlier that the nature of the security measure suggested that it was driven by intelligence of a possible attack. There could be concern about inadequate passenger screening or even conspiracies involving insiders - airport or airline employees - in some countries, he said.
Homeland Security Secretary John Kelly phoned lawmakers over the weekend to brief them on aviation security issues that have prompted the impending electronics ban, according a congressional aide briefed on the discussion. The aide was not authorized to speak publicly about the issue and spoke on the condition of anonymity.
The administration officials who briefed reporters about the ban said foreign officials were told about the impending order starting Sunday.
A U.S. government official said such a ban has been considered for several weeks. The official spoke on the condition of anonymity to disclose the internal security discussions by the federal government.
The ban would begin just before Wednesday's meeting of the U.S.-led coalition against the Islamic State group in Washington. A number of top Arab officials were expected to attend the State Department gathering. It was unclear whether their travel plans were related to any increased worry about security threats.
Another aviation-security expert, Jeffrey Price, said there could be downsides to the policy.
"There would be a huge disadvantage to having everyone put their electronics in checked baggage," said Price, a professor at Metropolitan State University of Denver. He said thefts from baggage would skyrocket, as when Britain tried a similar ban in 2006, and some laptops have batteries that can catch fire - an event easier to detect in the cabin than the hold.
Most major airports in the United States have a computer tomography or CT scanner for checked baggage, which creates a detailed picture of a bag's contents. They can warn an operator of potentially dangerous material, and may provide better security than the X-ray machines used to screen passengers and their carry-on bags. All checked baggage must be screened for explosives.
The Associated Press contributed to this report.